Low-Sidelobe Fixed-Frequency Leaky-Wave Antenna Using Amplitude-Phase Control and Decoupling Structure

This paper presents a dual-mode fixed-frequency leaky-wave antenna (LWA) array utilizing joint amplitude–phase control and a dedicated decoupling structure. The 38-element array is based on reconfigurable unit cells capable of 2-bit phase modulation through the combination of geometric and transmission phases, along with 1-bit amplitude modulation based on a reflection-cancellation mechanism. An amplitude–phase synthesis algorithm is developed to independently steer the main beam and reshape the sidelobe distribution, enabling precise manipulation of sidelobe positions while maintaining a stationary main beam direction. To overcome the performance degradation caused by practical mutual coupling, a dedicated decoupling structure is implemented to minimize excitation errors and restore modulation accuracy. Simulation results at a fixed frequency confirm that the decoupling structure contributes to a 3.8 dB gain enhancement and a 6 dB sidelobe level (SLL) reduction. The prototype demonstrates versatile dual-mode configurability: in the high-gain mode, it achieves a peak realized gain of 13.4 dBi; in the optimized low-SLL mode, it maintains a measured SLL below −14.0 dB across a scanning range of ±45°. With an overall beam-steering coverage exceeding 120°, the proposed LWA offers a robust and high-performance solution for advanced interference-sensitive communication systems.